In the prior art, heat exchanger design typically employs a series of tubing, and fins mounted to the tubes. The tubes act as conduits for fluid flow whereby heat from an operating device such as an air conditioner is brought to the heat exchanger. The fins that are mounted to the tubes facilitate the transfer of heat from the tubes to the surrounding media, which in most instances is the ambient environment.
While heat exchangers are used in a vast array of applications, one popular use is in the automotive field, wherein condensers as heat exchangers are used in conjunction with automotive air conditioning. These types of heat exchangers are made using essentially two different designs. A first design uses round tubing and bare fins that are mechanically attached to the round tubes by first lacing the tubes into holes punched in the fins, and then expanding the tubes to ensure that the tubes' outer surfaces are in close contact with the fins.
A second design uses a flat tubing having a plurality of channels in the tubing, commonly referred to as multivoid tubing. This type normally includes a number of parallel flow channels or passageways that are separated by webs or walls that run along the longitudinal axis of the tubing. Fluid to be cooled runs through the channels or passageways. In making these types of heat exchangers, the tubes are joined to corrugated fins using a brazing process.
In comparing the two types of tubing construction, it is more economical to manufacture tubing using the mechanical attachment technique with round tubes and fins, and these types of assemblies are popular for automotive and residential condenser use where cost considerations are important. However, the heat transfer efficiency is poor for these tubing assemblies as compared to those utilizing a brazed connection between the tubes and the fins. Thus, each type of tubing is not without its own drawback, either higher manufacturing cost or less than adequate heat transfer efficiency.
Therefore, a need exists for improved heat exchanger tubing that has high heat transfer efficiency and can be easily manufactured. The present invention solves this need by providing a heat exchanger tubing configuration that still uses fins for heat exchange, but does so without requiring either the expensive brazing step or the presence of a mechanical attachment between tubing and fins that compromises heat transfer efficiency.